Is All Non-Chlroine Shock The Same?

[swimgirl66]

I have a breand new Arctic ocean swim spa & while I'm happy with it so far, I am not happy with how much $ it may cost me to keep it balanced. I have the saltwater/ozone option but I've been told to shock it after every use (which is daily for one person). Since it is 1600 gallons, it needs 10-14 oz each day, which is about $4/day or $120/mo, which I wasn't counting on. That's the price from my dealer's brand (Apollo) and all it says on the bottle is "contains Potassium Monopersulfate". I've found better deals elsewhere, but I can't tell if they have the same formula. One says 43% PPMS...does anyone know if that will work? Appreciate any guidance...1st time spa owner.

[chem geek]

I think you mean MPS or KMPS which stands for potassium monopersulfate. Yes, most of the brands are the same and 43% MPS is about as strong as you get since the product is a triple salt so the MPS portion is 43% (the theoretical maximum would be 49.5%, but there's usually 3% peroxydisulfate and 2% magnesium carbonate impurities in standard product).

With a saltwater chlorine generator and an ozonator you should not need to use any non-chlorine shock. If your bather load is too high for the chlorine and ozone to handle, then you can just add more chlorine after your soak and that will be less expensive especially if you use bleach. However, you'll want to get some Cyanuric Acid (CYA) in your water and the easiest way to do that is to use Dichlor for a short while to build up the CYA and then switch to bleach. So basically take a look at the Dichlor/bleach Method In A Nutshell though to keep the pH more stable you'll probably want to have the Total Alkalinity (TA) lower at 50 ppm and want to add 50 ppm Borates (usually from boric acid you can get at DudaDiesel or The Chemistry Store.

As for how much chlorine to add after your soak, test your chlorine level an hour or so after your soak to make sure it's not too low and then again before your next soak. Just add enough so that you always have a reasonable chlorine level in the spa.

[swimgirl66]

Hi, Thanks for the thorough reply...I am still confused though by your statement: "With a saltwater chlorine generator and an ozonator you should not need to use any non-chlorine shock." That would be great news...but I am wondering why my dealer has made such a point of telling me to shock aggessively after every use? (The spa came with a 12-case of 2 lb. bottles of shock) Also, I CANNOT use bleach or chlorine...highly intolerant of them, which is why I chose this system in the first place. Also, I got a D in chemistry!!! So not my thing! This is the dark side of pool/spa ownership, having to figure out all this stuff & fiddle with it every day. I appreciate the wisdom of experienced owners!

[Dr. Spa]

Apparently not so intolerant as you think. A salt water system IS a chlorine system! The salt is electrically converted to CHLORINE right there in your spa.

[swimgirl66]

I do know that, but it's not the same as dumping chlorine into the water. With my system there is no smell, which is what affects my breathing & gives me headaches. So I won't be adding that directly into my spa, but thanks for trying to educate me.

[chem geek]

Yes, it IS the same as adding chlorine into the water. The difference is probably the level of chlorine and adding it concentrated you initially smell it at least when you are adding it.

OK then, if you can't add chlorine because you can't handle the smell of it in concentrated form (even Dichlor), then you can use the MPS from any reasonable non-chlorine shock product.

Probably your least expensive source for MPS would be the pool-sized product of GLB Oxy-Brite which is 41.3% MPS at $7.22 per pound. So 10-14 ounces weight per day would be $4.51 to $6.32 so your pricing is actually quite good. However, you should only need to add around 7 teaspoons (1.65 ounces weight) of non-chlorine shock for every person-hour of soaking. Where are you getting that you need to add 10-14 ounces weight of MPS? Though your swim spa is 1600 gallons, the MPS should not be degrading that quickly and the amount needed for your bather waste isn't very high. Are you measuring with MPS test strips?